aoc2023/day-18/util.go

package main

import (
	"bufio"
	"log"
	"math"
	"os"
	"regexp"
	"strconv"
)

// readlines reads lines from stdin.
// it returns them as an array of strings
func readlines() []string {
	lines := []string{}

	scanner := bufio.NewScanner(os.Stdin)
	for scanner.Scan() {
		lines = append(lines, scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		log.Fatal(err)
	}

	return lines
}

func getParams(rexp *regexp.Regexp, url string) map[string]string {
	match := rexp.FindStringSubmatch(url)

	m := make(map[string]string)
	for i, name := range rexp.SubexpNames() {
		if i > 0 && i <= len(match) {
			m[name] = match[i]
		}
	}
	return m
}

// mustConv converts string to int
// it will panic if an error occurs
func mustConv(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		panic(err)
	}
	return n
}

// mustConvHex converts a hex string to int
// it will panic if an error occurs
func mustConvHex(s string) int {
	n, err := strconv.ParseInt(s, 16, 64)
	if err != nil {
		panic(err)
	}
	return int(n)
}

// calculateArea returns the area of the polygon described by imager.space
func calculateArea(space []coords) int {
	area := 0
	for i := 0; i < len(space); i++ {
		next := space[(i+1)%len(space)]
		area += space[i].X*next.Y - space[i].Y*next.X
	}

	// add perimeter to area within perimeter
	area = len(space) + (int(math.Abs(float64(area))) / 2)

	return area - len(space)/2 + 1
}